This topic was brought up a while back, but I just had another encounter with the 15558WH timer malfunctioning. I had a customer call to tell me that their lights weren't coming on. When I arrived, there was no longer a programed on and off time (it somehow was erased). I replaced the timer to be on the safe side, but it happened again the very next day. The timer is being used on a 15PR900SS transformer (900w tranny). I've seen this problem several times before, but I haven't been able to figure out was causes the timer to lose it's program. It seems to happen in the 900s the most, but I've seen it on 600s also. Anybody have a clue as to why this is happening? I've got a call into Kichler, so hopefully they already know about this and can provide an answer.